1. The Field of the Invention
The invention relates to surgical clamps, and more particularly to surgical clamps which perform dual clamping functions. The present invention is designed for securely clamping a catheter for insertion within an anatomical duct and for thereafter clamping the duct around the catheter with an essentially constant clamping pressure so that the duct is adequately sealed without occluding the inserted catheter.
2. The Prior Art
Surgical clamps perform a vital function during any operative procedure. Surgical clamps function as an extension of the surgeon's hands, enabling the surgeon to hold and manipulate anatomical parts or other surgical instruments. Surgical clamps are often developed to make some step in a surgical procedure easier for the surgeon.
For example, operative cholangiography, since its introduction in 1932, has witnessed the development of various clamps and other devices to make the procedure faster, easier, and more reliable.
In performing operative cholangiography, the cystic duct is cleaned off near the gallbladder and is occluded with a tie or clamp depending on the surgeon's discretion. The cystic duct is then incised, creating an opening so that a catheter can be inserted within the duct. Next, the cystic duct catheter is grasped with a clamp and inserted into the opening of the cystic duct. After the catheter is inserted into the desired position (the catheter is to be in the common duct, but not so far that it is into the duodenum), the catheter is securely held in place by either a hemoclip or ligature. A radiopaque dye is thereafter injected through the cystic duct catheter and x-rays are taken (known as cholangiograms).
Operative cholangiography is basically an x-ray examination of the bile ducts to determine whether gallstones exist. The procedure is performed routinely during a cholecystectomy (removal of gallbladder) which is the second most common intraabdominal operation performed in the United States. If, after examining the cholangiogram, gallstones are observed in the bile ducts, they are removed before the cholecystectomy is completed.
In recent years, there has been considerable interest in developing improved methods of performing cholangiographies as well as improved surgical instruments for use in a cholangiography. Much of the attention has focused on the method of holding the catheter in position within the cystic duct.
For example, after the catheter has been inserted into the cystic duct it has been traditionally held in place with a ligature. Ligatures, however, are very inconvenient for the surgeon. They take time, and time is always a factor during any surgical procedure, particularly when the patient is under anesthetic. Furthermore, ligatures may damage the cystic duct.
Alternatively, surgeons have used hemoclips to hold the catheter in place after it has been inserted into the cystic duct. Hemoclips, which are designed specifically for occluding blood vessels, are fast and easy to use. However, it is very difficult to control how much pressure is placed on the hemoclip. As a result, the surgeon often inadvertently crushes the catheter when a hemoclip is applied. Only with much practice may hemoclips be applied without occluding the catheter or damaging the cystic duct. This is because most hemoclips are applied with a specially designed clamp which typically releases the hemoclip only after it has been fully clamped.
If the catheter is occluded, then the diagnostic dye cannot be injected into the common bile duct and a cholangiogram cannot be taken. In addition, once a hemoclip is in place it is difficult for the surgeon to release the hemoclip and remove the catheter from the cystic duct. Thus, although hemoclips have been advocated by some (see, e.g., Hampson, et al., "A Simple Method for Catheter Fixation of the Cystic Duct During Cholangiography," 159 Surgery, Gynecology, and Obstetrics 82-83 (1984), the use of hemoclips has several significant drawbacks.
One problem which has faced those skilled in the art is how to hold the catheter in place after it has been inserted within the cystic duct so that the catheter is not crushed and so that the diagnostic dye does not leak into the surrounding wound. An additional problem which has faced those skilled in the art is the necessity of using multiple clamps during cholangiography. For instance, one clamp is usually required to grasp and insert the catheter within the cystic duct and another clamp is used to hold the catheter within the cystic duct while a ligature or hemoclip is applied. Because the abdominal wound during cholangiography is so small and deep, multiple clamps are inconvenient.
Although various attempts to solve these problems have been made by those skilled in the art, to date there has not been devised an apparatus and method that have fully succeeded in achieving a solution to these problems.
One prior art approach to solve these problems has been the use of a single modified cystic duct clamp with two holes of different diameters drilled into its curved end. The smaller hole is designed for holding the catheter alone and the larger hole is designed for holding the catheter within the cystic duct while a ligature is applied. See, e.g., Taufic, "A Safe and Secure Technique of Cystic Duct Catheterization," 114 Archives of Surgery 749-51 (June 1979).
This technique has several significant drawbacks. Chief among them is that even though a single clamp instead of two is used, a ligature is still necessary to hold the catheter in place within the cystic duct. The clamp may not be used while the cholangiogram is taken because the clamp is made out of a radiopaque material which tends to interfere with the quality of the cholangiogram. Additionally, because the modified cystic duct clamp is of a traditional scissors-clamp configuration, the clamp takes up too much space within the small, deep wound.
Another prior art approach has been to use metal catheters instead of plastic catheters. This technique eliminates the risk of having the catheter crushed after a hemoclip is applied. Furthermore, metal catheters may be inserted within the cystic duct manually, thereby eliminating the need for a separate clamp to be used in inserting the catheter. See, e.g., Berci et al., "Improved Cannula for Operative (Cystic Duct) Cholangiography," 137 The American Journal of Surgery 826-28 (June 1979).
Despite its advantages, this technique is not preferred simply because a metal catheter is radiopaque and would therefore tend to interfere with the cholangiogram. Furthermore, a metal catheter with a fixed shape may easily perforate the cystic duct or common duct.
Yet another prior art approach to these problems has been to use a modified Borge clamp to hold the catheter in place within the cystic duct instead of a hemoclip or ligature. See, e.g., Berci et al., supra. The round hole of a normal clamp was milled square thereby giving the clamp a larger range of closure. Such a modified clamp holds the catheter tightly within the cystic duct but without occluding the catheter. In addition, it is easier to release the catheter in the cystic duct held with a clamp than to remove a hemoclip.
Although this technique has advantages compared to using a hemoclip to hold the catheter within the cystic duct, several disadvantages have been observed. Because the clamp is constructed out of a radiopaque material, the clamp tends to interfere with the desired cholangiogram. It is, therefore, possible that certain gallstones or other abnormalities might go undetected if such a clamp is used.
More importantly, the modified Borge clamp is a squeeze locking or ratchet clamp. The clamping pressure exerted at the "jaws" of the clamp is directly related to the quantity of material between the jaws. Thus, two identical clamps at the same ratchet position could be exerting vastly different clamping pressures depending on the material between the jaws. Therefore, there is a serious risk of damage to the duct or catheter when such clamps are used.
Still another approach that has been tried is to use a balloon catheter which will permit the diagnostic dye to be injected into the bile ducts and at the same time occlude the cystic duct so that no dye leaks into the surgical wound. Balloon catheters are inadequate for use in cholangiography because even a slight overinflation of the balloon could easily rupture the cystic duct.
In summary, none of the prior art techniques and apparatus developed to date provide adequate solutions to the problem of properly holding a catheter in place within the cystic duct, while eliminating the problems inherent in providing adequate securement of the catheter without occluding the x-rays, and without undue complication.
From the foregoing, it will be appreciated that what is needed in the art are apparatus and methods for clamping an anatomical duct into which a catheter has been inserted with an essentially constant clamping pressure which is not so great that the catheter is crushed nor too little that diagnostic dye is leaked into the abdominal wound.
Additionally, it would be a significant advancement in the art to provide apparatus and methods which perform the dual function of clamping a catheter prior to insertion within an anatomical duct and for thereafter securely clamping the duct around the catheter, so that only a single instrument need be used.
It would be another advancement in the art to provide an apparatus and method for a surgical clamp which readily accommodates use thereof in deep wounds or other congested operating sites.
It would be a further advancement in the art to provide an apparatus and method for use of a surgical clamp which is constructed out of a radiolucent material in the area of the duct so that the surgical clamp may be used while an x-ray is taken and will not interfere with the completed x-ray.
It would be yet another advancement in the art to provide an apparatus and method for use of a surgical clamp which can clamp an anatomical duct without damaging the duct.
The foregoing, and other features and objects of the present invention, are realized in the combination catheter and duct clamp which are disclosed and claimed herein.